![]() One may ask why it is so important not to use the "average temperature in a hospital"?. ![]() Of course, from the view of pure math it certainly not because you wrongly assumed the datarate is a constant value. I was wrong in my previous post speaking your calculation is right for the single frame. So it is worth to be mentioned that for a heavy graphics you must use the peak bandwith consumptions based on a LCD pixelcklock.Ĭontent originally posted in LPCWare by zp on Thu Sep 05 08:54: A tripple buffering is also impossible (more precicely - useless as it'll take more time than a double buffer scheme). Or even worse this means the exhausted FIFO. If more masters (SD, co-processor,GPDMA etc) are requesting the SDRAM, it does lead to more frequently LCD FIFO watermark level crossing and to round robin with a preference to LCD. This leads to the situation when only two masters can do long-term work on an AHB bus. for a fullscreen 3D rendering (i am working on) you need to refresh background, Z-buffer etc every frame. Of course, if you have a QVGA display or the static content in framebuffer, the SDRAM bandwidth does not get so big influence.īut in the single VGA mode and up LCD eats more than one third of the SDRAM bandwidth. The latter is just an average bandwidth for a one second basis but the peak value of 25.2 Mpixel/s does matter. You shoud use this value instead of (640x480圆0) = 18.432 Mpixel/s. This leads to the 25.2 Mpixel/s bandwidth. for a standard 640x480圆0Hz VGA the real horizontal pixel count is 800 and a full frame consists of 525 lines. It is obvious that every horizontal line for the LCD is bigger than a screen width. Though Data Rate is calculated quite right you can use this value if your framebuffer is about the same every frame. Then all other derivatives just rely on this. ![]() Your calculus treats Data Rate as a value of (Screen_width x Screen_Height x RefreshRate) Mpixels/s. Content originally posted in LPCWare by zp on Mon Sep 02 13:48:ĭear NXP, your LCD Bandwidth Calculator is wrong.
0 Comments
Leave a Reply. |